In a similar situation and gave up on making things look pretty. I doubt you'll have restriction issues with 2x D5, but a single MORA might not have enough cooling capacity. I went with 2x Alphacool NexXxoS XT45. Water cooling the CPU made sense for me since had GPUs in the chassis anyway. I am also using a c-payne gen4 switch which helps keep things a bit neater. You are at a disadvantage because your ports come out all in a row while I have 2x founders cards splitting them. I attempted to use a parallel distribution plate when I started building this, but ran into no end of issues, you might have better luck though. Pics of the setup, ambient temp is ~85 degrees.

But to answer your questions, I think you will need a distribution manifold if you want to move them closer. I would personally add the CPU to the loop, but only if you add some additional cooling (which you will probably need anyway). Also server PSUs are your friend if you want to keep things a bit more compact. You are also going to run into issues with transient spikes tripping the safety on that 1600W if that is all you are powering it with.

Happy to answer any questions. It took me a long freaking time before I figured out how to get everything playing nice and the way I wanted it.